KR102384827B1 - engine - Google Patents

Abstract

The engine includes a cylinder, a piston accommodated in the cylinder, a combustion chamber facing the piston, a sliding portion (large-diameter portion 114a) that strokes integrally with the piston, and a hydraulic surface exposed on the opposite side to the combustion chamber among the sliding portions; , a hydraulic pressure chamber 154a to which the hydraulic surface faces, and a floating pressure chamber 158b communicating with the hydraulic pressure chamber 154a, the volume of which changes according to the hydraulic pressure in the hydraulic pressure chamber 154a.

Description

engine

The present disclosure relates to an engine. This application claims the benefit of priority based on Japanese Patent Application No. 2018-050007 and Japanese Patent Application No. 2018-050008 filed on March 16, 2018, the content of which is incorporated in this application.

In marine engines, a crosshead type may be used. For example, in the engine of patent document 1, a sliding part is arrange|positioned in a crosshead, and when a sliding part operates by hydraulic pressure, the top dead center position of a piston moves. Thereby, the geometric compression ratio of the engine is varied.

Moreover, in an engine, when combustion maximum pressure becomes high too much, combustion temperature will rise and NOx in exhaust gas will increase. Therefore, in the engine of patent document 2, a hydraulic chamber is provided inside a piston. When the pressure in the combustion chamber rises, hydraulic oil is discharged from the hydraulic chamber, thereby depressing the crown surface of the piston. Thereby, the rise of the combustion maximum pressure is suppressed.

Japanese Patent Application Laid-Open No. 2014-020375 Japanese Patent No. 5273290

If both the mechanism for varying the compression ratio as described above and the mechanism for suppressing the maximum combustion pressure are provided, the structure becomes complicated. This is not limited to ships or crosshead types, but is a phenomenon that also occurs in other engines such as automobiles.

An object of the present disclosure is to provide an engine capable of suppressing the complexity of the structure in order to solve such a problem.

In order to solve the above problems, an engine according to an aspect of the present invention includes a cylinder, a piston accommodated in the cylinder, a combustion chamber facing the piston, a sliding part that strokes integrally with the piston, and a sliding part , a hydraulic surface exposed to the opposite side to the combustion chamber, a hydraulic chamber facing the hydraulic surface, and a floating pressure chamber communicating with the hydraulic pressure chamber and whose volume changes according to the hydraulic pressure in the hydraulic chamber.

The engine may include a hydraulic pump connected to the hydraulic chamber.

In the engine, a partition piston is slidably installed, and the interior is divided into a floating pressure chamber and an accommodation chamber by the partition piston, and a partition piston is installed from the accommodation chamber side to the floating pressure chamber side. You may provide the elastic member to press.

The engine is provided with a large-diameter hole in which the sliding part is accommodated, has a bottom surface opposite to the hydraulic surface, and a hydraulic chamber is formed between the hydraulic surface and the bottom surface, and a small-diameter hole is provided on the bottom surface of the large-diameter hole. The ball may be opened.

When the position in the stroke direction of the sliding part is within a predetermined range, one end is opened in the hydraulic chamber, and when the position in the stroke direction of the sliding part is in a direction away from the combustion chamber than the predetermined range, one end is closed, and the other end is closed. A communication path opened to the floating pressure chamber may be provided.

The communication path having one end open in the hydraulic chamber, the floating pressure chamber having the other end of the communication path open and whose volume changes according to the hydraulic pressure in the hydraulic chamber, and the hydraulic pressure in the hydraulic chamber or the pressure in the combustion chamber. In the case of exceeding the threshold value, the hydraulic chamber and the floating pressure chamber are made to communicate, and when the index value is equal to or less than the threshold value, a communication mechanism may be provided which makes the hydraulic pressure chamber and the floating pressure chamber non-communicating.

You may further provide the hydraulic pump connected to the hydraulic chamber, and the compression ratio control part which controls the hydraulic pump and changes the top dead center position of a piston.

According to the engine of the present invention, it becomes possible to suppress the complexity of the structure.

1 : is explanatory drawing which showed the whole structure of an engine.
Fig. 2 is an extraction view in which a connection portion between a piston rod and a crosshead pin is extracted.
3 is a functional block diagram of the engine.
4A and 4B are diagrams for explaining the combustion pressure suppression mechanism.
5 is an example of a P-V diagram of an engine.
6A and 6B are diagrams for explaining the first modified example.
7A and 7B are diagrams for explaining a second modified example.
Fig. 8 is a functional block diagram of the engine.
9 : is a figure for demonstrating a 3rd modified example.

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of this invention is described in detail, referring an accompanying drawing. The dimensions, materials, and other specific numerical values shown in the embodiments are merely examples for facilitating understanding, and do not limit the present disclosure unless specifically limited. In addition, in this specification and drawing, about the element which has substantially the same function and structure, the same code|symbol is attached|subjected, and duplicate description is abbreviate|omitted. In addition, elements not directly related to the present disclosure are omitted from illustration.

1 : is explanatory drawing which showed the whole structure of the engine 100. As shown in FIG. As shown in FIG. 1 , the engine 100 includes a cylinder 110 , a piston 112 , a piston rod 114 , a crosshead 116 , and a connecting rod 118 . and a crankshaft 120 , a flywheel 122 , a cylinder cover 124 , an exhaust valve case 126 , a combustion chamber 128 , an exhaust valve 130 , and an exhaust valve driving device 132 , an exhaust pipe 134 , a scavenge reservoir 136 , a cooler 138 , a cylinder jacket 140 , and a fuel injection valve 142 are included. .

A piston 112 is installed in the cylinder 110 . The piston 112 reciprocates in the cylinder 110 . One end of the piston rod 114 is attached to the piston 112 . A crosshead pin 150 of the crosshead 116 is connected to the other end of the piston rod 114 . The crosshead 116 reciprocates together with the piston 112 . The movement of the crosshead 116 in the left-right direction (direction perpendicular to the stroke direction of the piston 112) in FIG. 1 is restricted by the guide shoe 116a.

The crosshead pin 150 is axially supported by a crosshead bearing 118a provided at one end of the connecting rod 118 . The crosshead pin 150 supports one end of the connecting rod 118 . The other end of the piston rod 114 and one end of the connecting rod 118 are connected through a crosshead 116 .

The other end of the connecting rod 118 is connected to the crankshaft 120 . The crankshaft 120 is rotatable with respect to the connecting rod 118 . When the crosshead 116 reciprocates according to the reciprocating movement of the piston 112 , the crankshaft 120 rotates.

A flywheel 122 is mounted on the crankshaft 120 . The rotation of the crankshaft 120 and the like is stabilized by the inertia of the flywheel 122 . The cylinder cover 124 is provided on the upper end of the cylinder 110 . An exhaust valve case 126 is inserted into the cylinder cover 124 .

One end of the exhaust valve case 126 faces the piston 112 . An exhaust port 126a is opened at one end of the exhaust valve case 126 . The exhaust port 126a is opened to the combustion chamber 128 . The combustion chamber 128 faces the crown face of the piston 112 . The combustion chamber 128 is surrounded by the cylinder cover 124 , the cylinder 110 , and the piston 112 , and is formed in the cylinder 110 .

In the combustion chamber 128 , the valve body of the exhaust valve 130 is located. An exhaust valve driving device 132 is mounted on the rod portion of the exhaust valve 130 . The exhaust valve driving device 132 is disposed in the exhaust valve case 126 . The exhaust valve driving device 132 moves the exhaust valve 130 in the stroke direction of the piston 112 .

When the exhaust valve 130 moves toward the piston 112 and opens the valve, the exhaust gas generated in the cylinder 110 after combustion is exhausted from the exhaust port 126a. After exhaust, the exhaust valve 130 moves to the exhaust valve case 126 side, and the exhaust port 126a is closed.

The exhaust pipe 134 is attached to the exhaust valve case 126 and the supercharger C. The inside of the exhaust pipe 134 communicates with the exhaust port 126a and the turbine of the supercharger C. As shown in FIG. The exhaust gas exhausted from the exhaust port 126a is supplied to the turbine (not shown) of the supercharger C through the exhaust pipe 134, and then is exhausted to the outside.

Moreover, the active gas is pressurized by the compressor (not shown) of the supercharger C. Here, the active gas is, for example, air. The pressurized active gas is cooled by a cooler 138 in a scavenge reservoir 136 . The lower end of the cylinder 110 is surrounded by a cylinder jacket 140 . Inside the cylinder jacket 140, a scavenge chamber (掃气室; scavenge chamber) (140a) is formed. The active gas after cooling is press-fitted into the scavenging chamber 140a.

At the lower end side of the cylinder 110, a scavenging port 110a is provided. The scavenging port 110a is a hole penetrating from the inner peripheral surface of the cylinder 110 to the outer peripheral surface. A plurality of scavenging ports 110a are provided while being spaced apart in the circumferential direction of the cylinder 110 .

When the piston 112 moves toward the bottom dead center position from the scavenging port 110a, the active gas in the cylinder 110 from the scavenging port 110a due to the differential pressure in the scavenging chamber 140a and the cylinder 110. is inhaled

In addition, a fuel injection valve 142 is provided in the cylinder cover 124 . The tip of the fuel injection valve 142 is directed toward the combustion chamber 128 side. The fuel injection valve 142 ejects liquid fuel (fuel oil) to the combustion chamber 128 . Liquid fuel burns, and the piston 112 reciprocates by the expansion pressure.

FIG. 2 is an extraction view in which a connection portion between the piston rod 114 and the crosshead pin 150 is extracted. As shown in FIG. 2 , a flat portion 152 is formed on the outer peripheral surface of the crosshead pin 150 on the side of the piston 112 . The flat portion 152 extends in a direction substantially perpendicular to the stroke direction of the piston 112 .

A pin hole 154 (large diameter hole) is formed in the crosshead pin 150 . The pinhole 154 is opened to the flat portion 152 . The pinhole 154 extends from the flat portion 152 to the crankshaft 120 side (lower side in FIG. 2 ) along the stroke direction.

A cover member 160 is installed on the flat portion 152 of the crosshead pin 150 . The cover member 160 is mounted to the flat portion 152 of the crosshead pin 150 by means of a fastening member 162 . The cover member 160 covers the pinhole 154 . In the cover member 160 , a cover hole 160a penetrating in the stroke direction is formed.

The piston rod 114 includes a large-diameter portion 114a (sliding portion) and a small-diameter portion 114b. The outer diameter of the large-diameter portion 114a is larger than the outer diameter of the small-diameter portion 114b. The large-diameter portion 114a is formed at the other end of the piston rod 114 . The large-diameter portion 114a is inserted (accommodated) in the pinhole 154 of the crosshead pin 150 . The small-diameter portion 114b is formed on one end side of the piston rod 114 rather than the large-diameter portion 114a. The small-diameter portion 114b is inserted into the cover hole 160a of the cover member 160 .

The hydraulic chamber 154a is formed inside the pinhole 154 . The pinhole 154 is partitioned in the stroke direction by the large-diameter portion 114a. The large-diameter portion 114a is located on the top dead center position side of the piston 112 in the hydraulic chamber 154a. The hydraulic chamber 154a is a space on the bottom surface 154b side of the pinhole 154 partitioned by the large-diameter portion 114a. Of the large-diameter portion 114a, the hydraulic surface 114a1 exposed on the opposite side to the combustion chamber 128 (in Fig. 2, the lower side) is the surface on the bottom surface 154b of the oil pressure chamber 154a and the pinhole 154. do. The oil pressure chamber 154a is formed between the oil pressure surface 114a1 and the bottom surface 154b.

The side wall of the hydraulic chamber 154a (that is, the side wall 154c of the pinhole 154) extends in the stroke direction. One end of an oil passage 156 is opened in the bottom surface 154b of the pinhole 154 . The other end of the oil passage 156 is opened to the outside of the crosshead pin 150 . A hydraulic pipe 170 is connected to the other end of the oil passage 156 .

A hydraulic pump 172 communicates with the hydraulic pipe 170 . That is, the hydraulic pump 172 is connected to the hydraulic chamber 154a. A check valve 174 is installed between the hydraulic pump 172 and the oil passage 156 . The flow of hydraulic oil from the oil passage 156 side to the hydraulic pump 172 side is suppressed by the check valve 174 . Hydraulic oil is press-in (sent out) from the hydraulic pump 172 to the hydraulic chamber 154a through the oil passage 156 .

In addition, a branch pipe 176 is connected between the oil passage 156 and the check valve 174 among the hydraulic pipes 170 . A switching valve 178 is provided in the branch pipe 176 . The switching valve 178 is, for example, an electromagnetic valve. During operation of the hydraulic pump 172 , the selector valve 178 is closed. When the switching valve 178 is opened while the hydraulic pump 172 is stopped, hydraulic oil is discharged from the hydraulic chamber 154a to the branch pipe 176 side. The side of the switching valve 178 opposite to the oil passage 156 communicates with an oil tank (not shown). The discharged hydraulic oil is stored in the oil tank. The oil tank supplies hydraulic oil to the hydraulic pump 172 .

The large-diameter portion 114a slides on the inner peripheral surface of the pinhole 154 in the stroke direction according to the oil amount of the hydraulic oil in the hydraulic chamber 154a. The large-diameter portion 114a slides with respect to the side wall 154c according to the amount of hydraulic oil in the hydraulic chamber 154a. As a result, the piston rod 114 moves in the stroke direction. The piston 112 moves (stroke) integrally with the piston rod 114 (large-diameter portion 114a). When the amount of hydraulic oil inside the hydraulic chamber 154a is increased, the top dead center position of the piston 112 moves toward the combustion chamber 128 . When the hydraulic oil inside the hydraulic chamber 154a is reduced, the top dead center position of the piston 112 moves toward the bottom dead center position. In this way, the top dead center position of the piston 112 becomes variable.

That is, the engine 100 is provided with the compression ratio variable mechanism V. As shown in FIG. The compression ratio variable mechanism V includes the above-described hydraulic chamber 154a and the large-diameter portion 114a of the piston rod 114 . The compression ratio variable mechanism V makes the compression ratio variable by moving the top dead center position of the piston 112 .

Here, the case where one hydraulic chamber 154a is provided has been described. However, among the pinholes 154 partitioned by the large-diameter portion 114a, the space 154d on the cover member 160 side may also be a hydraulic chamber. This hydraulic chamber may be used independently or may be used together with the hydraulic chamber 154a.

3 is a functional block diagram of the engine 100 . In Fig. 3, the configuration mainly related to the control of the compression ratio variable mechanism V is shown. As shown in FIG. 3 , the engine 100 includes a control device 180 . The control device 180 is configured of, for example, an ECU (Engine Control Unit). The control unit 180 is constituted by a central processing unit (CPU), a ROM in which programs and the like are stored, a RAM as a work area area, and the like, and controls the entire engine 100 . In addition, the control device 180 functions as the compression ratio control unit 182 .

The compression ratio control unit 182 controls the hydraulic pump 172 and the switching valve 178 to change (move) the top dead center position of the piston 112 . In this way, the compression ratio control unit 182 controls the geometric compression ratio of the engine 100 .

4A and 4B are diagrams for explaining the combustion pressure suppression mechanism P. FIG. Fig. 4 (a), Fig. 4 (b) is an extraction diagram of the same location as in Fig. 2 . As shown in Fig. 4A, the engine 100 includes a combustion pressure suppression mechanism P. The combustion pressure suppression mechanism P includes the hydraulic chamber 154a described above, the small-diameter hole 158 , the partition piston 164 , and the elastic member 166 .

The small-diameter hole 158 is opened in the bottom surface 154b of the pinhole 154 . The small-diameter hole 158 extends in the stroke direction continuously from the hydraulic chamber 154a of the pinhole 154 . That is, the side wall 158a of the small-diameter hole 158 extends in the stroke direction. The inner diameter of the small-diameter hole 158 is smaller than the inner diameter of the pinhole 154 (hydraulic chamber 154a).

The partition piston 164 is slidably installed in the small-diameter hole 158 . The partition piston 164 divides the small-diameter hole 158 into the floating pressure chamber 158b and the accommodation chamber 158c. The floating pressure chamber 158b is located on the oil pressure chamber 154a side rather than the partition piston 164. The accommodation chamber 158c is located on the side spaced apart from the oil pressure chamber 154a rather than the partition piston 164.

The floating pressure chamber 158b is continuous to the hydraulic pressure chamber 154a. A part of the hydraulic oil supplied to the hydraulic pressure chamber 154a flows into the floating pressure chamber 158b. The partition piston 164 is pressed toward the accommodation chamber 158c side by the hydraulic pressure of hydraulic oil.

An elastic member 166 is disposed in the accommodation chamber 158c. The elastic member 166 is constituted by, for example, an elastic spring. The elastic member 166 moves the partition piston 164 against the hydraulic pressure of the hydraulic oil, from the storage chamber 158c side to the floating pressure chamber 158b side (the hydraulic chamber 154a side, the piston rod 114 side). press with

When the piston 112 is pressed toward the bottom dead center by the combustion pressure of the combustion chamber 128 , the large-diameter portion 114a is pressed toward the hydraulic chamber 154a, and the hydraulic pressure in the hydraulic chamber 154a rises. When the hydraulic pressure in the oil pressure chamber 154a rises, the partition piston 164 is pressed toward the accommodation chamber 158c side. Therefore, as shown in Fig. 4(b), the partition piston 164 moves to the storage chamber 158c side. As a result, the elastic member 166 is compressed, and the elastic force for pressing the partition piston 164 increases. The partition piston 164 stops at a place where the pressing force by hydraulic pressure and the pressing force by the elastic force are balanced.

As a result, the volume of the floating pressure chamber 158b becomes large. In this way, the volume of the floating pressure chamber 158b changes according to the internal hydraulic pressure. By that much, the hydraulic oil flows into the floating pressure chamber 158b from the hydraulic pressure chamber 154a. As the amount of oil in the hydraulic oil in the hydraulic chamber 154a decreases, the large-diameter portion 114a moves toward the bottom surface 154b. Therefore, the piston 112 moves toward the bottom dead center position. As a result, the combustion chamber 128 expands, and the combustion maximum pressure of the combustion chamber 128 is suppressed.

When the piston 112 moves to the bottom dead center position side and the pressure in the combustion chamber 128 decreases, the hydraulic pressure in the oil pressure chamber 154a decreases. The pressing pressure by the hydraulic pressure for pressing the partition piston 164 becomes smaller than the pressing pressure by the elastic force, and the partition piston 164 moves to the hydraulic chamber 154a side. Hydraulic oil flows into the hydraulic chamber 154a from the floating pressure chamber 158b. In this way, the combustion pressure suppression mechanism P functions as an accumulator of hydraulic oil.

5 is an example of a P-V diagram of the engine 100 . In the example shown in FIG. 5, it is assumed that the switching valve 178 of the compression ratio variable mechanism V is closed, and the hydraulic pump 172 is stopped. As shown by the dashed-dotted line in FIG. 5, the theoretical combustion cycle of the engine 100 is a combination of constant-volume combustion and constant-pressure combustion. It is a sabathe cycle (compound cycle). However, in reality, static combustion and static pressure combustion are not completely realized as in the comparative example shown by the broken line in FIG. Specifically, the maximum combustion pressure P2 of the comparative example becomes higher with respect to the maximum combustion pressure P1 of the server cycle. Therefore, combustion temperature rises and NOx in exhaust gas will increase.

In the engine 100, the combustion maximum pressure P3 is suppressed lower than the combustion maximum pressure P2 of the comparative example by the combustion pressure suppression mechanism P as mentioned above. That is, the maximum combustion pressure P3 approaches the maximum combustion pressure P1 of the server cycle. By evacuating the hydraulic oil to the floating pressure chamber 158b according to the pressure of the combustion chamber 128, it becomes possible to bring a part of the combustion cycle close to the constant pressure combustion.

In this way, in the engine 100 , an increase in the combustion temperature is suppressed by the combustion pressure suppression mechanism P, and NOx in the exhaust gas is suppressed. Moreover, since the combustion maximum pressure P3 is suppressed, the member strength enough to withstand the combustion maximum pressure P2 of a comparative example is not calculated|required. In addition, as mentioned above, the oil pressure chamber 154a is shared with the compression ratio variable mechanism V and the combustion pressure suppression mechanism P. Therefore, compared with the case where the oil pressure chamber 154a for the compression ratio variable mechanism V and the oil pressure chamber 154a for the combustion pressure suppression mechanism P are separately provided, the complexity of the structure is suppressed.

Further, when the compression ratio is increased by the compression ratio variable mechanism V, the maximum combustion pressure is also increased. In the combustion pressure suppression mechanism P, the deformation amount of the elastic member 166 is proportional to the pressure of the combustion chamber 128 . Therefore, when it is set to a high compression ratio by the compression ratio variable mechanism V, the elastic member 166 deform|transforms large, and it is easy to suppress the rise of the combustion maximum pressure. On the other hand, when the compression ratio is low, the amount of deformation of the elastic member 166 is small, and the influence on the combustion maximum pressure is suppressed.

6A and 6B are diagrams for explaining the first modified example. As shown in FIG. 6A , in the combustion pressure suppression mechanism Pa of the engine 200 of the first modification, the small-diameter hole 158 is sealed by the cover member 210 . . The cover member 210 divides the pinhole 154 and the small-diameter hole 158 . Specifically, among the small-diameter holes 158 , a flange groove 158d is formed on the inner peripheral surface of the end of the pinhole 154 side. The cover member 210 is provided with a step portion 210a. The step portion 210a is fitted into the flange groove 158d.

The communication path 220 is provided in the crosshead pin 150 . One end of the communication path 220 is opened in the side wall 154c of the pinhole 154 . The floating pressure chamber 158b is sandwiched by the partition piston 164 and the cover member 210 . The other end of the communication path 220 is opened to the cover member 210 side among the side walls 158a of the floating pressure chamber 158b.

As shown in FIG. 6B , one end of the communication path 220 is closed by the large-diameter portion 114a depending on the position of the large-diameter portion 114a. Further, as shown in FIG. 6A , one end of the communication path 220 is opened without being closed by the large-diameter portion 114a depending on the position of the large-diameter portion 114a. In other words, with respect to the opening of the communication path 220 formed in the side wall 154c of the pinhole 154 , the large-diameter portion 114a faces a direction orthogonal to the stroke direction and a direction orthogonal to the stroke direction. may become non-opposite.

That is, the length from one end of the communication path 220 to the cover member 160 is longer than the thickness of the large-diameter portion 114a in the stroke direction. The communication path 220 opens one end to the hydraulic chamber 154a when the large-diameter portion 114a is within a predetermined range. When the large-diameter portion 114a is on the side (the side of the sub-hydraulic chamber 158b) spaced apart from the combustion chamber 128 by a predetermined range, one end of the communication path 220 is closed.

The predetermined range is, for example, a predetermined position shown in FIG. 6B and a range on the combustion chamber 128 side from the predetermined position. However, the predetermined position may be the piston 112 side (in the figure, upper side) rather than the illustrated position, or the floating pressure chamber 158b side may be sufficient. What is necessary is just a position where at least one end of the communication path 220 can be closed by the large-diameter part 114a.

In this way, when the large-diameter portion 114a is within a predetermined range, the communication path 220 communicates the hydraulic pressure chamber 154a and the floating pressure chamber 158b. Therefore, when the large-diameter portion 114a is within the predetermined range, the hydraulic pressure in the hydraulic pressure chamber 154a acts on the partition piston 164 on the floating pressure chamber 158b side.

Further, when the large-diameter portion 114a is on the side of the floating pressure chamber 158b beyond the predetermined range, the hydraulic pressure chamber 154a and the floating pressure chamber 158b do not communicate. Therefore, when the large-diameter portion 114a is on the side of the floating pressure chamber 158b beyond the predetermined range, the hydraulic pressure of the oil pressure chamber 154a does not act on the partition piston 164 on the side of the floating pressure chamber 158b. That is, the combustion pressure suppression mechanism Pa does not function.

Here, the compression ratio when the large-diameter portion 114a is at the predetermined position is defined as the predetermined pressure ratio. Then, you can change it to: That is, when the compression ratio is controlled to be equal to or greater than a predetermined pressure ratio by the compression ratio variable mechanism V, the combustion pressure suppression mechanism Pa functions. When the compression ratio is controlled to be less than the predetermined pressure ratio by the compression ratio variable mechanism V, the combustion pressure suppression mechanism Pa does not function.

As described above, when the compression ratio is increased by the compression ratio variable mechanism V, the maximum combustion pressure is also increased. When the compression ratio variable mechanism V exceeds a predetermined pressure ratio, the elastic member 166 is greatly deformed, and a rise in the maximum combustion pressure is suppressed. When it is less than the predetermined pressure ratio, since the combustion maximum pressure does not fall, the fall of thermal efficiency is avoided.

7A and 7B are diagrams for explaining a second modified example. As shown in FIG. 7A , in the combustion pressure suppression mechanism Pb of the engine 300 of the second modification, the small-diameter hole 158 is sealed by the cover member 210 as in the first modification. do. The floating pressure chamber 158b is sandwiched by the partition piston 164 and the cover member 210 . One end of the communication path 220 is opened on the cover member 210 side among the side walls 158a of the floating pressure chamber 158b. The communication path 220 is provided in the crosshead pin 150 .

Unlike the first modification, in the second modification, one end of the communication path 220 is opened in the bottom surface 154b of the pinhole 154 . However, one end of the communication path 220 may be opened at the same position as in the first modification.

A control valve 330 is provided in the communication path 220 . The control valve 330 is, for example, a solenoid valve. The communication path 220 is opened and closed by the control valve 330 . As shown in Fig. 7A, when the control valve 330 closes the valve, the hydraulic pressure chamber 154a and the floating pressure chamber 158b do not communicate. As shown in Fig. 7B, when the control valve 330 opens the valve, the hydraulic pressure chamber 154a and the floating pressure chamber 158b communicate.

In addition, the hydraulic pressure pipe 170 is provided with a hydraulic pressure sensor Sa. The hydraulic pressure in the hydraulic pressure chamber 154a communicating with the hydraulic pipe 170 is detected by the hydraulic pressure sensor Sa.

8 is a functional block diagram of the engine 300 . In Fig. 8, the configuration mainly related to the control of the compression ratio variable mechanism V and the communication mechanism CMa is shown. As shown in FIG. 8 , the engine 300 includes a communication mechanism CMa. The communication mechanism CMa includes the above-described communication path 220 , the hydraulic pressure sensor Sa, the control valve 330 , and the valve control unit 340 .

The control device 180 functions as the valve control unit 340 in addition to the compression ratio control unit 182 described above. The valve control unit 340 opens the control valve 330 when the oil pressure detected by the oil pressure sensor Sa exceeds a preset first threshold value (threshold value). The valve control unit 340 closes the control valve 330 when the oil pressure detected by the oil pressure sensor Sa is equal to or less than the first threshold value.

That is, the communication mechanism CMa causes the hydraulic pressure chamber 154a and the floating pressure chamber 158b to communicate when the hydraulic pressure in the hydraulic pressure chamber 154a exceeds the first threshold value. That is, when the oil pressure in the oil pressure chamber 154a exceeds the first threshold value, the combustion pressure suppression mechanism Pb functions. The communication mechanism CMa makes the oil pressure chamber 154a and the floating pressure chamber 158b out of communication when the oil pressure of the oil pressure chamber 154a is below a 1st threshold value. That is, when the oil pressure in the oil pressure chamber 154a becomes equal to or less than the first threshold value, the combustion pressure suppression mechanism Pb does not function.

As mentioned above, when the hydraulic pressure of the hydraulic pressure chamber 154a exceeds a 1st threshold value, the combustion maximum pressure is also high. At this time, by opening the control valve 330 , the elastic member 166 is greatly deformed, and a rise in the maximum combustion pressure is suppressed. When the hydraulic pressure in the oil pressure chamber 154a is equal to or less than the first threshold value, the combustion maximum pressure does not drop, so that a decrease in thermal efficiency is avoided. Since the oil pressure in the oil pressure chamber 154a tends to directly interlock with the combustion pressure, the combustion pressure suppression mechanism Pb functions appropriately when the maximum combustion pressure is high.

Here, a case in which the control valve 330 is controlled by the valve control unit 340 has been described. However, when the hydraulic pressure in the hydraulic chamber 154a exceeds the first threshold value, the communication path 220 opens the valve, and when the hydraulic pressure in the hydraulic pressure chamber 154a is equal to or less than the first threshold value, the communication path 220 is when the valve is closed. For example, a hydraulic circuit that operates in this way may be used.

9 : is a figure for demonstrating a 3rd modified example. As shown in FIG. 9 , in the engine 400 of the third modification, the communication mechanism CMb includes the pressure sensor Sb, the control valve 330 , and the valve control unit 440 . The pressure sensor Sb detects the pressure in the combustion chamber 128 .

The control device 180 functions as a valve control unit 440 in addition to the above-described compression ratio control unit 182 . When the pressure in the combustion chamber 128 detected by the pressure sensor Sb exceeds a preset second threshold value (threshold value), the valve control unit 440 opens the control valve 330 . The valve control unit 440 closes the control valve 330 when the pressure in the combustion chamber 128 detected by the pressure sensor Sb becomes equal to or less than the second threshold value.

When the pressure in the combustion chamber 128 exceeds the second threshold value, the maximum combustion pressure is increased. As in the second modification described above, by opening the control valve 330 , the elastic member 166 is greatly deformed, and the increase in the combustion maximum pressure is suppressed. When the pressure in the combustion chamber 128 is equal to or less than the second threshold value, since the combustion maximum pressure does not fall, a decrease in thermal efficiency is avoided. Since the pressure in the combustion chamber 128 is measured, the combustion pressure suppression mechanism Pb functions appropriately when the maximum combustion pressure is high.

Here, the case in which the control valve 330 is controlled by the valve control unit 440 has been described. However, similarly to the second modification described above, when the pressure in the combustion chamber 128 exceeds the second threshold value, the communication path 220 opens the valve, and the pressure in the combustion chamber 128 is equal to or less than the second threshold value. When the communication path 220 closes the valve. For example, a hydraulic circuit that operates in this way may be used.

As described in the second modification and the third modification, the hydraulic pressure in the hydraulic chamber 154a or the pressure in the combustion chamber 128 determines the communication or non-communication between the hydraulic pressure chamber 154a and the floating pressure chamber 158b. It is used as an index value for

Also in the 1st modification, the 2nd modification, and the 3rd modification, it becomes possible to approximate a part of a combustion cycle to static pressure combustion similarly to the above-mentioned embodiment. As a result, a rise in combustion temperature is suppressed, and NOx in exhaust gas is suppressed. Further, since the combustion peak pressure is suppressed, high member strength is not required. Compared with the case where the oil pressure chamber 154a for the compression ratio variable mechanism V and the oil pressure chamber 154a for the combustion pressure suppression mechanisms Pa and Pb are separately provided, the complexity of the structure is suppressed.

As mentioned above, although one Embodiment was demonstrated, referring an accompanying drawing, it goes without saying that this indication is not limited to the said embodiment. It is clear that those skilled in the art can come to various changes or modifications within the scope described in the claims, and it is understood that these naturally fall within the technical scope of the present invention.

For example, in the above-described embodiments and modifications, two-cycle type, uniflow scavenging type, crosshead type engines 100 , 200 , 300 , (400) has been described as an example. However, the type of engine is not limited to a two-cycle type, a uniflow scavenging type, and a crosshead type. At least it's an engine. In addition, the engine 100 is not limited to the object for ships, For example, the object for automobiles may be sufficient.

In addition, in the above-mentioned embodiment and modified example, the case where liquid fuel was used was demonstrated. However, for example, gaseous fuel may be used. In this case, in addition to the fuel injection valve 142 , a gaseous fuel injection valve is provided in the vicinity of the scavenging air port 110a or in a portion of the cylinder 110 from the scavenging port 110a to the cylinder cover 124 . Fuel gas flows in in the cylinder 110, after being injected from a gaseous fuel injection valve. When a small amount of liquid fuel is injected from the fuel injection valve 142, a mixture of fuel gas and active gas is ignited and combusted by the combustion heat. In this case, the P-V diagram is close to the auto cycle instead of the server cycle shown in Fig. 5 . Here, the fuel gas gasifies LNG, LPG (liquefied petroleum gas), light oil, heavy oil, and the like. In addition, the dual fuel type which separates gaseous fuel and liquid fuel may be sufficient as the engine 100, for example.

In addition, in the above-mentioned embodiment and modified example, the case where the partition piston 164 and the elastic member 166 are provided was demonstrated. However, the partition piston 164 and the elastic member 166 are not essential components. At least, there should be a mechanism in which the volume of the floating pressure chamber 158b is changed according to the hydraulic pressure inside the floating pressure chamber 158b.

In addition, in the above-described embodiments and modifications, the case in which the floating pressure chamber 158b is formed in the small-diameter hole 158 continuous to the pinhole 154 has been described. In this case, the processing to form the floating pressure chamber 158b becomes easy. However, the floating pressure chamber 158b is not limited to the configuration formed in the small-diameter hole 158 . The floating pressure chamber 158b may communicate with the hydraulic pressure chamber 154a at least.

In addition, in the above-mentioned embodiment and modified example, the case where the oil pressure chamber 154a is provided in the crosshead pin 150 of the crosshead 116 was demonstrated. However, the hydraulic chamber may be provided in either of the piston 112 , the piston pin, and the crosshead 116 . At least, the hydraulic surface of the sliding portion that strokes integrally with the piston 112 should just be in contact with the hydraulic chamber.

In addition, in the above-mentioned modified example, the case where the compression ratio variable mechanism V (compression ratio control part 182) was provided was demonstrated. However, the compression ratio variable mechanism V is not an essential configuration.

[Industrial Applicability]

The present disclosure can be applied to an engine.

100, 200, 300, 400: engine, 110: cylinder, 112: piston, 114a: large diameter part (sliding part), 114a1: hydraulic surface, 128: combustion chamber, 154: pinhole (large diameter hole), 154a: hydraulic chamber, 154b : bottom surface, 158: small diameter hole, 158b: floating pressure chamber, 158c: accommodation chamber, 164: partition piston, 166: elastic member, 172: hydraulic pump, 182: compression ratio control unit, 220: communication path, CMa, CMb: communication Instrument

Claims (7)

cylinder;
a piston accommodated in the cylinder;
a combustion chamber facing the piston;
a sliding part that strokes integrally with the piston;
a hydraulic surface exposed to the side opposite to the combustion chamber among the sliding parts;
a hydraulic chamber facing the hydraulic surface;
a hydraulic pump connected to the hydraulic chamber;
a compression ratio variable mechanism for changing a top dead center position of the piston using the hydraulic pump;
a floating pressure chamber communicating with the hydraulic chamber and having a volume changed according to the hydraulic pressure in the hydraulic chamber;
a small-diameter hole in which a partition piston is slidably installed, and the interior is partitioned into the floating pressure chamber and the accommodation chamber by the partition piston; and
an elastic member for pressing the partition piston from the storage chamber side to the floating pressure chamber side; and
A large diameter hole in which the sliding part is accommodated and having a bottom surface opposite to the hydraulic surface, the hydraulic chamber being formed between the hydraulic surface and the bottom surface
including,
The small-diameter hole is opened on the bottom surface of the large-diameter hole,
The hydraulic pump is connected to the hydraulic chamber through a flow path opened in the bottom surface of the large-diameter hole,
engine. According to claim 1,
When the position in the stroke direction of the sliding part is within a predetermined range, one end is opened into the hydraulic chamber, and when the position in the stroke direction of the sliding part is in a direction away from the combustion chamber than the predetermined range, the one end The engine further comprising a communication path that is closed and the other end is opened to the floating pressure chamber. According to claim 1,
a communication path having one end open to the hydraulic chamber;
a floating pressure chamber in which the other end of the communication path is opened and the volume of which is changed according to the hydraulic pressure in the hydraulic chamber; and
When an index value that is the hydraulic pressure in the hydraulic chamber or the pressure in the combustion chamber exceeds a threshold value, the hydraulic chamber and the floating pressure chamber communicate with each other, and when the index value is less than or equal to the threshold value, the hydraulic pressure The engine further comprising; a communication mechanism for making the seal and the floating pressure chamber non-communicable. delete delete delete delete

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